JPH09144758A - Dynamic pressure bearing device and disk driving device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent shaft supporting property while sufficient dynamic thrust pressure is obtained even at a relatively low speed with a simple and compact device, and to excellently apply an air dynamic pressure bearing device to various kinds of devices such as a hard disk drive(HDD). SOLUTION: A groove to produce the radial dynamic pressure of a radial bearing part 26 to perform the shaft-support of a rotary body 25 in the radial direction is of dynamic pressure groove shape to forcibly feed the air toward a pressure chamber 31a of a thrust bearing part 31. The rotary body 25 is levitated in the axial direction to perform the shaft-support of the rotary body 25 in the thrust direction with the air pressure stored in the pressure chamber 31a of the thrust bearing part 31 due to the forcible feeding effect of the radial bearing part 26, and the thrust shaft supporting force is automatically adjusted by the flow resistance of a pressure adjusting part 31b from the pressure chamber 31a of the thrust bearing part 31 to an air guide hole 32 in a fixed shaft 22, and the vibration suppression function is improved by the damper function of the pressure chamber 31a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing device and a disk using the same, in which a dynamic pressure of air is generated in a radial bearing portion and a thrust bearing portion to support a shaft in a radial direction and a thrust direction. A drive device.

[0002]

2. Description of the Related Art In recent years, in various devices such as motors, various dynamic pressure bearing devices utilizing air dynamic pressure have been studied and proposed. In a conventional dynamic pressure bearing device, for example, a rotating body is rotatably fitted to a fixed shaft, and a radial dynamic pressure generating groove is formed on the outer peripheral surface side of the fixed shaft. The radial bearing portion is constituted by. Further, a thrust bearing portion is formed between the shaft end surface (upper end surface in the drawing) of the fixed shaft and the axially opposed surface of the rotating body, and the dynamic pressure of the air interposed in the radial bearing portion and the thrust bearing portion described above. Thus, the rotating body is rotatably supported on the fixed shaft.

[0003]

However, such a bearing device utilizing air dynamic pressure generally has a fluid viscosity of several thousandth of that of a bearing dynamic pressure utilizing oil dynamic pressure, and therefore the physical constitution is generally small. However, there is a problem that the entire apparatus tends to be large in size, and sufficient air dynamic pressure cannot be obtained unless it is used at high speed rotation, and especially the shaft support characteristics and vibration suppression function in the thrust direction are not good. Therefore, conventionally, it has been considered difficult to adopt a bearing device using air dynamic pressure for a device such as a hard disk drive (HDD) that is required to be downsized and that rotates at a relatively low speed. . In addition, in a bearing device using air dynamic pressure, some dust is inevitably generated due to rubbing at the time of starting and stopping, which hinders devices such as hard disk drive (HDD) that requires high cleanliness. .

Further, in the air dynamic pressure bearing device, since the rotating body is floated and rotated by interposing air, it is in an insulating state. Therefore, when applied to a hard disk drive (HDD), for example, static electricity generated in the hard disk is generated. Easily accumulates on the rotating body side, and due to the accumulated static electricity,
When an MR type (magnetoresistive type) head is used, the head portion may be damaged.

Therefore, the present invention provides an air dynamic bearing device which is simple and small in size, can sufficiently obtain thrust dynamic pressure and radial dynamic pressure even at relatively low speed rotation, and is excellent in shaft support characteristics and vibration suppression function. The first purpose is to do so.

In addition to the first object, the present invention provides
A second object is to provide an air dynamic pressure bearing device excellent in cleanliness and a disk drive device using the same.

Further, in addition to the above first and second objects, a third object of the present invention is to provide an air dynamic pressure bearing device excellent in static elimination property and a disk drive device using the same.

[0008]

In order to achieve the first object, the invention according to claim 1 is characterized in that both surfaces of a fixed shaft and a rotating body rotatably fitted to the fixed shaft are opposed to each other in the circumferential direction. A groove for radial dynamic pressure generation is formed on at least one side of the above to provide two radial bearing portions in the axial direction, and thrust between the upper end surface of the fixed shaft and the axially opposed surface of the rotating body. A dynamic pressure bearing device configured to rotatably support a rotating body with respect to the fixed shaft by a dynamic pressure of air interposed between the radial bearing portion and the thrust bearing portion, wherein the radial bearing The radial dynamic pressure generating groove provided in the portion is formed into a dynamic pressure groove shape for sending air toward the thrust bearing portion side, and an air guide hole penetrating the fixed shaft from the upper end to the lower end of the fixed shaft. To The thrust bearing portion includes a pressure chamber for storing the air pumped from the radial bearing portion between the shaft end surface of the fixed shaft and the axially facing surface of the rotating body, and a narrow space from the pressure chamber to the air guide hole. And a pressure adjusting portion including an air passage.

According to a second aspect of the present invention, the pressure chamber according to the first aspect is arranged annularly on the outer peripheral side of the shaft end surface of the fixed shaft, and the diameter at the boundary position between the pressure chamber and the pressure adjusting portion is: It has a configuration of ¼ to ⅔ of the outer diameter of the fixed shaft.

Further, in the invention according to claim 3, the pressure adjusting part according to claim 1 axially projects at least one side of the axial end surface of the fixed shaft and the axially opposite surface of the rotating body toward the other side. The pressure adjusting section is configured by narrowing the air passage extending from the pressure chamber to the opening of the air guide hole.

Furthermore, the invention according to claim 4 is characterized in that the pressure adjusting part according to claim 1 is provided between the pressure chamber and the air guide hole, and the narrow air passage forming surface in the pressure adjusting part is radial. It has a configuration provided as a plane orthogonal or intersecting with the facing surface forming the bearing portion.

On the other hand, the invention according to claim 5 uses the dynamic pressure bearing device according to claim 1, 2 or 3 or 4, wherein the stator and rotor of the motor are fixed shaft side and rotor side. The motor frame integrally extending from the fixed shaft of the stator part is fixed to the main body of the apparatus to isolate the whole motor from the external atmosphere, and the disk is attached to the rotating body to drive the rotation. The air guide hole provided in the dynamic pressure bearing device is configured to open to the outside atmosphere side of the device body.

According to a sixth aspect of the present invention, there is provided a static eliminating member for electrically connecting the rotating body in the disk drive device according to the fifth aspect to the fixed shaft side, and the static eliminating member is connected to the fixed shaft and the rotating body. It is arranged in the central part.

According to the means having the structure described in claim 1, the rotating body is axially supported in the radial direction by the high pressure air pressurized in the radial dynamic pressure generating groove of the radial bearing portion. At the same time, the high pressure air in the radial bearing portion is pumped into the pressure chamber that constitutes the thrust bearing portion, and the pressure of the air stored in the pressure chamber causes the rotor to float in the axial direction and be axially supported in the thrust direction. . Further, since the air is discharged to the outside of the shaft through the inside of the shaft, the dust can be discharged well.

At this time, the air in the pressure chamber of the thrust bearing portion is sent into the air guide hole through the pressure adjusting portion while receiving the flow resistance corresponding to the weight of the rotating body, thereby the thrust bearing portion. The air pressure in the pressure chamber that composes is always automatically adjusted to an appropriate pressure. Further, since the air in the pressure chamber functions as a damper against the axial moving force, the vibration suppression function of the bearing is improved.

Further, at this time, if the pressure chamber and the pressure adjusting portion are provided as in the second aspect, particularly good thrust supporting force can be obtained.

Further, in particular, as described in claim 3, the air passage is narrowed by the step portion in which at least one side of the axial end surface of the fixed shaft and the axially opposite surface of the rotating body is projected in the axial direction to narrow the air passage, and the pressure adjusting portion. If the above is formed, the pressure adjusting portion can have a simple structure.

Further, by disposing the pressure adjusting portion as described in claim 4, flow resistance in the pressure adjusting portion can be efficiently obtained in a small space.

On the other hand, according to the apparatus of claim 5, the dust generated in the disk drive device is discharged toward the outside atmosphere through the air guide hole of the dynamic pressure bearing device, and the disk drive device. The inside is kept clean.

If a static eliminating member for conducting the rotating body to the fixed shaft side is provided as described in claim 6, the static electricity accumulated on the rotating body side is eliminated through the fixed shaft side, and the MR type When a (magneto-resistive) head is used, damage to the head portion due to static electricity is favorably prevented.

At this time, if the static elimination member is arranged on the center side where the rotational peripheral speed is low, the generation of dust due to contact of the static elimination member is minimized, and even if dust is generated, the dust will be The air is discharged well to the outside through the air guide hole, and the cleanliness of the static eliminator is not impaired.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments in which the present invention is applied to a disk drive device having a fixed HDD spindle motor will be described in detail below with reference to the drawings.

First, the overall structure of the disk drive device will be described. In the disk drive device shown in FIG. 7,
The HDD spindle motor 12 and the carriage 13 fixed on the base plate 11 are hermetically covered by a cover case 14, and the inside of the cover case 14 is isolated from the external atmosphere and is kept in a clean state. In addition, external air is passed through the filter 16 attached to the ventilation hole 15 of the side wall 14a of the cover case 14 to the cover case 1
4, the air in the cover case 14 is exhausted through the inside of the HDD spindle motor 12 to the outside atmosphere.

A plurality of hard disks 17 are mounted on the HDD spindle motor 12 so as to be separated from each other in the axial direction by a predetermined distance so as to be stacked, and are attached to respective tip portions of a plurality of arms 13a extending from the carriage 13. Further, the head portions are arranged facing each other on both sides of each of the hard disks 17 in a floating state.

On the other hand, the HDD spindle motor 12
Is equipped with a bearing device that utilizes air dynamic pressure. The structure of the HDD spindle motor 12 and the structure of the air dynamic pressure bearing device will be described below.

As shown in FIG. 1, the above-mentioned HD
The D spindle motor 12 is composed of a stator set assembled to the side of the motor frame 21 made of a substantially disc-shaped aluminum material, and a rotor set axially assembled to the stator set. The motor frame 21 is fixed to the base plate 11 (see FIG. 6) of the disk drive device body described above.

A fixed shaft 22 is integrally provided so as to stand vertically at a substantially central position of the motor frame 21 of the HDD spindle motor 12, and the base end portion of the fixed shaft 22 made of this aluminum material. (Bottom end in the figure)
A stator core 24 having salient poles around which the winding wire 23 is wound is mounted on the outer periphery of the boss portion provided on the.

Further, a hub 25 as a rotating body is rotatably fitted on the outer periphery of the body of the fixed shaft 22. The hub 25 is formed of a cup-shaped aluminum material having a substantially hollow cylindrical shape. The hub 25 has an inner peripheral wall surface and the fixed shaft 22.
A pair of radial bearing portions 26, 26 is formed between the circumferentially facing surfaces of the outer circumferential wall surface of the. The pair of radial bearing portions 26, 26 are arranged side by side in the axial direction, and a predetermined air dynamic pressure is obtained by the pumping action of the radial dynamic pressure generating groove formed on the outer peripheral wall surface of the fixed shaft 22. It is designed to support the shaft in the radial direction by air dynamic pressure.

As described above, the hub 25 and the fixed shaft 2
If 2 and 2 are formed of the same aluminum material, the fluctuation of the bearing gap can be suppressed even when the temperature environment changes.

The outer peripheral wall surface of the fixed shaft 22 in which the radial dynamic pressure generating groove is formed, and the shaft end surface of the upper end of the fixed shaft 22 shown in the figure may come into contact with the hub 25 side at the time of starting and stopping. Therefore, the coating layer 27 made of a lubricating resin containing ceramics or polyamide-imide is deposited and formed on these portions.
This prevents abrasion and burning.

A pair of radial dynamic pressure generating grooves 28, 28 as shown in FIG. 2 are axially recessed in the outer peripheral coating layer 27 of the fixed shaft 22. Each of the radial dynamic pressure generating grooves 28 has a dynamic pressure groove shape extending in a certain inclination direction, and the hub 25 side moves from the right side to the left side in the figure, so that a thrust bearing portion side described later is formed. It is provided so as to send air in the axial direction toward (upper side in the drawing).
Both radial dynamic pressure generating grooves 28, 28 are fixed shaft 2
Two dividing grooves 29 circumferentially provided at a substantially central portion in the axial direction are sandwiched, and are separated by a predetermined distance in the axial direction.

On the other hand, a thrust bearing portion 31 is provided at the tip portion (upper end portion in the figure) of the fixed shaft 22.
The thrust bearing portion 31 is formed between the shaft upper end surface on the tip side of the fixed shaft 22 and the axially facing surface of the hub 25 as the rotating body described above.
The hub 25 is floated in the axial direction by the dynamic pressure of the air interposed between the hub 25 and the hub 25, thereby supporting the shaft in the thrust direction. The detailed structure of the thrust bearing portion 31 will be described later.

On the other hand, the fixed shaft 22 is attached to the fixed shaft 2.
An air guide hole 32 is formed so as to extend axially outward along the central axis of the second reference numeral 2. This air guide hole 32
The opening on the upper end side in the figure of FIG. 1 opens toward the thrust bearing portion 31 provided on the upper end side of the motor in the figure, and the opening on the lower end side of the air guide hole 32 in the figure
It opens toward the atmosphere on the outside of the disk device body described above. The upper portion of the air guide hole 32 in the drawing is narrowed to a small diameter, and the opening to the thrust bearing portion 31 is also small in diameter.

Next, the structure of the thrust bearing portion 31 described above will be described. The thrust bearing portion 31 includes a shaft upper end surface of the fixed shaft 22 at the upper end portion in the figure and the hub 2.
5 is formed between the opposing surfaces in the axial direction, and is composed of a pressure chamber 31a and a pressure adjusting portion 31b which are air passages defined between the opposing surfaces. Of these, the pressure chamber 31a is annularly arranged on the outer peripheral side of the shaft end surface of the fixed shaft 22, and the pressure adjusting portion 31b is arranged on the inner peripheral side of the pressure chamber 31a.

In the pressure chamber 31a, the outer peripheral portion of the pressure chamber 31a is communicated with the radial bearing portion 26 described above, whereby the air pressure-fed by the radial dynamic pressure generating groove 28 is transferred to the pressure chamber 31a. It is stored in a high pressure state inside and is configured to obtain a predetermined thrust levitation force. The diameter d at the boundary position between the pressure chamber 31a and the pressure adjusting portion 31b is 1/4 of the outer diameter D of the fixed shaft 22.
The length is set to 2/3.

On the other hand, the pressure adjusting portion 31b comprises a narrow air passage extending from the inner peripheral side portion of the pressure chamber 31a to the upper end opening of the air guide hole 32 described above, and the pressure resistance of the narrow air passage causes the pressure chamber 31a to flow. The air pressure in 31a is adjusted to an appropriate pressure. The narrow air passage forming the pressure adjusting portion 31b is defined between a step portion 31c provided on the hub 25 side and a tip end surface of the fixed shaft 22 facing the step portion 31c in the axial direction. There is.
The step portion 31c is formed by projecting a central portion of the hub 25 toward the fixed shaft 22 side (downward side in the drawing) in a thin-walled cylindrical shape, and includes a pressure adjusting portion 31b defined by the step portion 31c. Through the air guide hole 32.
It is configured to communicate with the side.

Further, at the central portion of the step portion 31c on the hub 25 side which constitutes the pressure adjusting portion 31b, a static eliminating member 33 made of a conductive string-like member is provided so as to hang down in the air guide hole 32. Has been. The free end portion (lower end portion in the figure) of the static elimination member 33 is the air guide hole 32.
Is arranged so as to come into contact with the inner peripheral wall of, and the hub 25 side is electrically connected to the fixed shaft 22 side by the static elimination member 33.

In the apparatus according to such an embodiment, first, the hub 25 as a rotating body is axially moved in the radial direction by the high pressure air boosted by the radial dynamic pressure generating grooves 28, 28 of the radial bearing portions 26, 26. Supported. Further, the high pressure air generated in the radial bearing portions 26, 26 is subjected to the upward pressure feeding action of the radial dynamic pressure generating grooves 28, 28 so that the pressure chamber 31 constituting the thrust bearing portion 31 is formed.
By being fed into the pressure chamber a and the high-pressure air is stored in the pressure chamber 31a, the hub 25 floats in the axial direction to support the shaft in the thrust direction.

Further, the high-pressure air in the pressure chamber 31a is sent into the air guide hole 32 of the fixed shaft 22 through the pressure adjusting portion 31b, but the air in the pressure adjusting portion 31b is transferred to the hub 25. And the weight of the disk mounted on the hub 25, and the like, and flow while receiving a flow resistance according to the total weight of the rotating body. As a result, the air pressure in the pressure chamber 31a forming the thrust bearing portion 31 is always automatically adjusted to an appropriate pressure according to the total weight of the rotating body.

According to such a shaft supporting structure, the shaft is supported with almost no so-called bearing loss, and the pressure chamber 31a of the thrust bearing portion 31 has a damper function for the axial moving force. Therefore, it is possible to satisfactorily prevent axial fluctuations due to axial vibration, etc.
A stable rotation state can be obtained.

At this time, if the pressure adjusting portion 31b of the thrust bearing portion 31 is formed by narrowing the air passage by the step portion 31c as in the present embodiment, the pressure adjusting portion 3 is formed.
1b can have a simple configuration.

Further, the diameter d at the boundary position between the pressure chamber 31a of the thrust bearing portion 31 and the pressure adjusting portion 31b is ¼ to ⅔ of the outer diameter D of the fixed shaft 22 as in this embodiment. If the length is set, good thrust bearing force can be obtained.

Further, if the pressure adjusting portion 31b is arranged in the axial center portion of the fixed shaft 22 and the hub 25 as in this embodiment, the flow resistance in the pressure adjusting portion 31b can be efficiently obtained in a small space. .

On the other hand, in the apparatus of this embodiment, as described above, the air in the cover case 14 of the disk drive device is exhausted to the outside atmosphere through the air guide hole 32 of the dynamic pressure bearing device in the HDD spindle motor 12. Therefore, the dust generated in the disk drive device is also discharged toward the outside atmosphere through the air guide hole 32 of the dynamic pressure bearing device, so that the inside of the disk drive device is kept clean. To be done.

Further, in the apparatus of this embodiment, the hub 25 as a rotating body is fixed to the fixed shaft 22 via the static eliminating member 33.
Since it is conducted to the side, the static electricity accumulated on the side of the hub 25 is removed through the fixed shaft 22 side, and especially when an MR type (magnetoresistive type) head is used, damage to the head portion due to static electricity is good. To be prevented.

At this time, if the static eliminating member 33 is arranged on the center side where the rotational peripheral speed is low as in the present embodiment,
Since the contact of the static elimination member 33 is performed at a low speed, the generation of dust by the static elimination member 33 is minimized, and even if dust is generated, the dust is generated by the air guide hole 3
It will be satisfactorily discharged to the outside through 2
The cleanliness inside the disk drive is not impaired.

In the apparatus according to the embodiment shown in FIG. 3 in which the corresponding components are designated by the same reference numerals, in the vicinity of the external discharge portion on the lower side of the air guide hole 32 in the drawing,
Circulating air passages 41 to the stator side are formed so as to radially pass therethrough. The circulating air passage 41 is configured to discharge a part of the air flowing from the thrust bearing portion 31 through the air guide hole 32 to the inner peripheral side of the stator core 24. The same operation and effect can be obtained also by the embodiment apparatus having such an air circulation system.

The embodiments of the invention made by the present inventor have been specifically described above, but the invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. Needless to say. For example, the step portion 31c constituting the pressure adjusting portion 31b is not limited to the one provided on the hub 25 side, that is, the rotating body side as in the above-described embodiment, but may be provided on the fixed shaft 22 side or both. It is also possible to provide.

The static elimination member 33 used in the present invention is
The brush is not limited to the above-mentioned string-like member, and a conductive brush or the like can be used. In this case, for example, as shown in FIGS. 4 and 5, a ring-shaped frame 42 mounted in the air guide hole 32 of the fixed shaft 22.
In addition, the conductive brush 43 is supported so as to project to the hub 25 side through three radially extending spring bodies 43, and a part of the conductive brush 43 is brought into contact with the hub 25 side. Can be considered.

Further, the step portion constituting the pressure adjusting portion according to the present invention is a conical step portion 45 as shown in FIG.
It is also possible to use the inclined side surface of the step portion 45 to form the pressure adjusting portion 46 from an inclined narrow air passage. According to such an embodiment device, the fluid resistance in the pressure adjusting unit 46 can be obtained in a smaller space.

The dynamic pressure bearing device according to the present invention can be similarly applied to a dynamic pressure bearing device used for other than the HDD motor.

[0052]

As described above, in the air dynamic pressure bearing device according to the first aspect of the present invention, the radial dynamic pressure generating groove of the radial bearing portion for axially supporting the rotating body in the radial direction is provided with the thrust bearing portion. Of the dynamic pressure groove group that sends air to the pressure chamber of the thrust bearing, and the air pressure accumulated in the pressure chamber of the thrust bearing part is caused by the pressure feeding action of this radial bearing part to levitate the rotor in the axial direction and In addition to supporting the shaft, the thrust shaft supporting force is automatically adjusted by the flow resistance of the pressure adjusting part from the pressure chamber of the thrust bearing part to the air guide hole of the fixed shaft, and the anti-vibration suppressing function is provided by the damper function of the pressure chamber. Since it is configured to increase, it is possible to obtain a good shaft support characteristic while sufficiently obtaining thrust dynamic pressure even at a relatively low speed rotation with a simple and compact device. A hard disk drive (HD
The air dynamic bearing device can be favorably applied to various devices such as D).

Further, if the pressure chamber and the pressure adjusting portion are set as in the second aspect of the present invention, a particularly good thrust supporting force can be obtained, and the above-mentioned effects can be obtained even better.

According to claim 3 of the present invention,
If the pressure adjusting portion is formed by narrowing the air passage by a step portion that axially projects at least one side of the axial end surface of the fixed shaft and the axially facing surface of the rotating body, the pressure adjusting portion can be simplified. Therefore, the above-described effects can be more favorably obtained.

Further, by arranging the pressure adjusting portion as in the fourth aspect of the present invention so as to efficiently obtain the flow resistance in the pressure adjusting portion in a small space, the above-mentioned effect can be obtained more satisfactorily. be able to.

On the other hand, as in claim 5 according to the present invention,
If the dust generated in the disk drive device is discharged toward the outside atmosphere through the air guide hole of the dynamic pressure bearing device to improve the cleanliness inside the disk drive device, in addition to the above effects Therefore, the reliability of the disk drive device can be further improved.

At this time, as described in claim 6 according to the present invention, a static eliminating member for conducting the rotating body to the fixed shaft side is provided, and static electricity accumulated on the rotating body side is eliminated through the fixed shaft side, and the head by static electricity is discharged. By configuring so as to prevent damage to the parts, in addition to the effects described above, the reliability of the disk drive device can be further improved, especially when an MR (magnetoresistive) head is used.

Further, at this time, the static elimination member is arranged on the center side where the rotational peripheral speed is low, so that the generation of dust due to the contact of the static elimination member can be suppressed to the minimum, and even if dust is generated, the dust will be guided through the air guide hole. If it is configured to be discharged to the outside through the through, it is possible to satisfactorily eliminate static electricity without impairing the cleanliness, and in addition to the above-mentioned effects, it is possible to further improve the reliability of the disk drive device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory diagram showing an HDD spindle motor using a dynamic pressure bearing device according to an embodiment of the present invention.

2 is an enlarged view showing a radial bearing portion provided in the dynamic pressure bearing device of the HDD spindle motor shown in FIG. 1, in which (a) is a side view and (b) is a developed view. is there.

FIG. 3 is a cross-sectional explanatory view showing an HDD spindle motor using a dynamic pressure bearing device according to another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view showing another embodiment of the static elimination stage member.

5 is an explanatory plan view of the static elimination step member shown in FIG. 4. FIG.

FIG. 6 is a cross-sectional explanatory view showing another embodiment of the pressure adjusting portion in the thrust bearing portion.

FIG. 7 is an explanatory cross-sectional view showing the overall structure of the disk drive device.

[Explanation of symbols]

 22 fixed shaft 25 hub (rotating body) 26 radial bearing part 28 radial dynamic pressure generating groove 31 thrust bearing part 31a pressure chamber 31b pressure adjusting part 31c step part 32 air guide hole 33 static eliminator

Claims (6)

[Claims] 1. A radial dynamic pressure generating groove is formed on at least one side of both opposing surfaces in the circumferential direction of a fixed shaft and a rotating body that is rotatably fitted to the fixed shaft to form a radial bearing portion. The thrust bearing portion is provided between the axial upper end surface of the fixed shaft and the axially opposite surface of the rotating body, and the dynamic pressure of air interposed between the radial bearing portion and the thrust bearing portion is provided at two locations in the axial direction. In the dynamic pressure bearing device configured to rotatably support the rotating body with respect to the fixed shaft, the radial dynamic pressure generating groove provided in the radial bearing portion,
The thrust bearing portion is formed into a dynamic pressure groove shape for sending air under pressure, and an air guide hole penetrating from the upper end to the lower end of the fixed shaft is formed in the fixed shaft. A pressure chamber for storing the air pumped from the radial bearing portion between the shaft end surface of the shaft and the axially opposite surface of the rotating body, and a pressure adjusting portion including a narrow air passage extending from the pressure chamber to the air guide hole. A hydrodynamic bearing device characterized in that 2. The pressure chamber according to claim 1 is annularly arranged on the outer peripheral side of the shaft end surface of the fixed shaft, and the diameter at the boundary position between the pressure chamber and the pressure adjusting portion is relative to the outer diameter of the fixed shaft. The dynamic pressure bearing device is characterized in that it is set to 1/4 to 2/3. 3. The pressure adjusting portion according to claim 1, which has a step portion in which at least one side of the axial end surface of the fixed shaft and the axially facing surface of the rotating body is axially projected toward the other side. A hydrodynamic bearing device characterized in that a pressure adjusting portion is configured by narrowing an air passage from the pressure chamber to the opening of the air guide hole by the step portion. 4. The pressure adjusting portion according to claim 1 is provided between the pressure chamber and the air guide hole, and the narrow air passage forming surface of the pressure adjusting portion forms a radial bearing portion. A hydrodynamic bearing device characterized by being provided as a plane orthogonal to or intersecting a plane. 5. A dynamic pressure bearing device according to claim 1, 2 or 3 or 4, wherein a stator part and a rotor part of a motor are respectively arranged on a fixed shaft side and a rotor side, and a stator part is provided. The motor frame integrally extending from the fixed shaft of the device is fixed to the main body of the apparatus to isolate the entire motor from the external atmosphere, and the disk is attached to the rotating body to drive the rotation of the rotating body. A disk drive device characterized in that an air guide hole provided in the bearing device is opened to the outside atmosphere side of the device body. 6. A static eliminator for electrically connecting the rotating body in the disk drive device according to claim 5 to a fixed shaft side, and the static eliminator is arranged at a central side portion of the fixed shaft and the rotary body. A disk drive device characterized by.